563 results about "Noise floor" patented technology

An apparatus and method provide non-intrusive in-service testing of audio/video synchronization testing without using traditional audio marker tones. The network includes an A/V synchronous test signal generator which injects video and audio markers into the video and audio non-intrusively and routes the two signals into a switch where they are switched into a channel for encoding and transmission via the ATM network. At the distant end the signal is decoded and routed by a switch into the A/V test generator and measurement set where the markers are detected and the A/V skew calculated, after which the audio and video are routed to the subscriber. The A/V test set signal generator includes a Video Blanking Interval (VBI) test signal generator and a white noise generator, the former injecting a marker into the video signal and the later injecting an audio marker into the audio signal. The video marker is injected into the VBI and broadband, background audio noise to measure the delay between the audio and video components of a broadcast. The marking of the audio is accomplished by gradually injecting white noise into the audio channel until the noise level is 6 dB above the noise floor of the audio receiver. As a precursor A/V sync signal, a small spectrum of the white noise is notched or removed. This signature precludes inadvertent recognition of program audio noise as the audio marker.

A method and apparatus for estimating the presence of RF interference in a wireless data channel is described. The method and apparatus comprises a set of identical tracking/register (T/R) filter blocks, each T/R filter block associated and corresponding to an RF channel of interest. Each T/R filter block includes a pair of tracking/register (T/R) filters. Power/magnitude estimates from an RSSI calculation are input to the T/R filter blocks. One T/R filter is used to estimate the noise floor (in the absence of interference). The T/R filter latches and filters the lowest input values received from a power/magnitude circuit. The other T/R filter estimates the level of an interferer, if present, by latching and filtering the largest valued outputs of the power/magnitude circuit.

A system and method for controlling amplification of a signal received by a ZIF radio having a power level within a full power range relative to a minimum noise floor. The ZIF radio includes a ZIF receiver front end, an overload detector, an ADC, a saturation detector, a DC and power estimator, and control logic. The control logic utilized full visibility of the ADC to limit gain of the baseband amplifier to a maximum gain setting sufficient to view the minimum noise floor and to view a received signal having a power level within any of several segments of the power spectrum. The segmentation of the power spectrum is based on an overload condition of the ZIF receiver front end and a saturation condition of the ADC. The control logic further employs limited gain stepping of the baseband amplifier to avoid exceeding a DC budget of the ADC.

Interference classification with minimal or incomplete information. Receivers in access points and in other network devices on a wireless digital network may be switched to a spectrum monitor mode in which they provide amplitude-versus-frequency information for a chosen part of the spectrum. This may be performed by performing a FFT or similar transform on the signals from the receiver. Receivers are calibrated with known interference sources in controlled environments to determine peaks, pulse frequency, bandwidth, and other identifying parameters of the interference source in best and worst case conditions. These calibrated values are used for matching interference signatures. Calibration is also performed using partial signatures collected over a short period in the order of microseconds. These partial signals may be used to detect interferers while scanning. Another aspect of the invention is to record the variation of noise floor in the presence of interference sources. Multiple interference sources may be detected. While data collection is performed in one or more APs, classification may be performed in the

AP or on other systems associated with the network collecting and processing spectrum information from one or more APs.

A novel and useful apparatus for and method of determining the channel order and channel estimate in a communications system such as a wireless communication system including cellular and cordless. Such channels are typically characterized by rapidly changing impulse response and their taps can be modeled as zero-mean, complex, Gaussian random processes. A sufficiently long, initial channel estimate of length is performed so as to ensure that the actual channel taps will be contained in the estimated taps thus making certain that the equalizer will effectively eliminate intersymbol interference. Channel estimation is performed during each burst using the training sequence transmitted in the middle of the burst. The tap energies are averaged so as to track slow variations in the pattern of resultant channel taps. A noise floor is calculated using the lowest averaged taps and a threshold is computed based thereon and applied to the average taps. The channel order and the tap positions are then selected in accordance those average taps that are above the threshold.

A new optical sensing device containing fiber Bragg gratings, a scanning bandpass filter, an interferometer and multiple photodetectors is disclosed. The present invention also describes a new system and method for fibre Bragg grating (FBG) sensor interrogation and multiplexing. The new system combines a scanning Fabry-Perot (SFP) bandpass filter used to wavelength-multiplex multiple gratings in a single fiber, and an unbalanced Mach-Zehnder fibre interferometer made with a 3x3 coupler to detect strain-induced wavelength shifts. A passive technique for interferometer drift compensation using non-sensing FBGs is included in the system. A complete prototype system interrogates four gratings in a single fiber at a Nyquist sampling rate up to 10 kHz, with a noise floor measured near 4 nepsi Hz-½ above 0.1 Hz. The inclusion of the interferometer drift compensation technique is shown to make quasi-static measurements feasible.

A security system comprises a secured asset associated with a high-sensitivity GPS receiver that can receive network aiding information. Indoors, the pseudo-ranges from orbiting GPS satellites can be computed by using digital correlators to pull directly received satellite signal transmissions from the noise floor, but the NAV-data transmissions cannot be demodulated well enough due to the attenuation caused by the building structure. So a wireless network is relied upon to provide aiding information that supplies the almanac and ephemeredes. The fact that the NAV-data transmissions cannot be demodulated well enough is taken as indicia that the system is being operated indoors, and such can be used in a geo-fence control to decide if indoor or outdoor use is not permitted. The secured asset can be temporarily or permanently disabled according to such geo-fence controls.

An exemplary embodiment of the present invention described and shown in the specification and drawings is a transceiver with a receiver, a transmitter, a local oscillator (LO) generator, a controller, and a self-testing unit. All of these components can be packaged for integration into a single IC including components such as filters and inductors. The controller for adaptive programming and calibration of the receiver, transmitter and LO generator. The self-testing unit generates is used to determine the gain, frequency characteristics, selectivity, noise floor, and distortion behavior of the receiver, transmitter and LO generator. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or the meaning of the claims.

An exemplary embodiment of the present invention described and shown in the specification and drawings is a transceiver with a receiver, a transmitter, a local oscillator (LO) generator, a controller, and a self-testing unit. All of these components can be packaged for integration into a single IC including components such as filters and inductors. The controller for adaptive programming and calibration of the receiver, transmitter and LO generator. The self-testing unit generates is used to determine the gain, frequency characteristics, selectivity, noise floor, and distortion behavior of the receiver, transmitter and LO generator. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or the meaning of the claims.

A system for detecting the level of the noise floor due to circuit noise as seen at the ADC for a wireless receiver. The system measures power after digitizing and filtering, and subtracts off any variable gain used in the analog front end to determine differentially the size of the signal at the antenna. The system further differentially detects the signal size of any incoming signal at the antenna in a similar fashion, and determines its size relative to the measured noise floor. If the level of the circuit noise of the receiver is known absolutely, the absolute signal size of the incoming signal can likewise be determined with this inventive method and system.

To alleviate the requirement to back-off all up-link performance, such as by limiting power spectral density, to overcome far-end cross-talk problems otherwise associated with relatively short loop-length wireline links, the present invention partitions the frequency spectrum based on an estimate of the loop length of a subscriber unit (CPE) modem from an exchange (LTE) modem. Up to a threshold frequency (fmax) at which received transmissions from a subscriber having a longest loop length (115) become indistinguishable by the LTE modem from a noise floor (102), up-link performance on all loop lengths is limited to correspond to that of the longest loop. At frequencies above the threshold frequency (fmax), subsets of subscribers (152-154) having relatively short loop lengths (116-119) use high frequency carriers that have signal to noise ratios sufficient to support information transmission in these elevated frequency bands.

An exemplary embodiment of the present invention described and shown in the specification and drawings is a transceiver with a receiver, a transmitter, a local oscillator (LO) generator, a controller, and a self-testing unit. All of these components can be packaged for integration into a single IC including components such as filters and inductors. The controller for adaptive programming and calibration of the receiver, transmitter and LO generator. The self-testing unit generates is used to determine the gain, frequency characteristics, selectivity, noise floor, and distortion behavior of the receiver, transmitter and LO generator. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or the meaning of the claims.

A method and apparatus to encoding or decoding an audio signal is provided. In the method and apparatus, a noise-floor level to use in encoding or decoding a high frequency signal is updated according to the degree of a voiced or unvoiced sound included in the signal.

An exemplary embodiment of the present invention described and shown in the specification and drawings is a transceiver with a receiver, a transmitter, a local oscillator (LO) generator, a controller, and a self-testing unit. All of these components can be packaged for integration into a single IC including components such as filters and inductors. The controller for adaptive programming and calibration of the receiver, transmitter and LO generator. The self-testing unit generates is used to determine the gain, frequency characteristics, selectivity, noise floor, and distortion behavior of the receiver, transmitter and LO generator. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or the meaning of the claims.

Impairment or other conditions (e.g., signal to noise ratio or noise floor) in a data-over-cable system are represented graphically in an easy to use and comprehensible manner, enabling quick identification and isolation of the source of the impairment. The graphical representation of the condition, referred to herein as an "impairment circle", is in the form of a circular template with a line segment superimposed thereon representing the impairment. One end of the line segment is placed on the perimeter of the circle at a location associated with a particular cable modem or channel. The other end of the line segment either terminates in the interior of the circle or terminates on another portion of the perimeter. The perimeter of the circle can be divided into multiple sections, each section representing a channel in a transmission path. The sections can be further divided into multiple divisions, each division corresponding to a particular cable modem in the path or number of occurrences. In one type of the impairment circle, the location in which the line segment terminates within the interior of the circle indicates the magnitude of the impairment or other measurement. A single impairment circle can be used to represent impairments or other measurements of multiple channels and multiple cable modems. In another type of impairment circle, the line segment goes from one division of one section to another division of another section, indicating a condition of impairment of other channels when a particular cable modem in one channel is active. Different colors for the line segments and different widths of the line segments can convey additional information, such as the number of occurrences of the condition, or the magnitude of the impairment.